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Date: Wed, 18 Oct 2017 13:13:44 -0700
From: Christoph Paasch <cpaasch@...le.com>
To: Yuchung Cheng <ycheng@...gle.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
ncardwell@...gle.com, maheshb@...gle.com
Subject: Re: [PATCH net-next] tcp: socket option to set TCP fast open key
Hello Yuchung,
On 18/10/17 - 11:22:51, Yuchung Cheng wrote:
> New socket option TCP_FASTOPEN_KEY to allow different keys per
> listener. The listener by default uses the global key until the
> socket option is set. The key is a 16 bytes long binary data. This
> option has no effect on regular non-listener TCP sockets.
can you explain what the use-case is to have per-listener TFO keys?
Thanks,
Christoph
>
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>
> ---
> include/net/request_sock.h | 2 ++
> include/net/tcp.h | 5 +++--
> include/uapi/linux/tcp.h | 1 +
> net/ipv4/sysctl_net_ipv4.c | 3 ++-
> net/ipv4/tcp.c | 33 +++++++++++++++++++++++++++
> net/ipv4/tcp_fastopen.c | 56 +++++++++++++++++++++++++++++++++-------------
> net/ipv4/tcp_ipv4.c | 1 +
> 7 files changed, 82 insertions(+), 19 deletions(-)
>
> diff --git a/include/net/request_sock.h b/include/net/request_sock.h
> index 23e22054aa60..347015515a7d 100644
> --- a/include/net/request_sock.h
> +++ b/include/net/request_sock.h
> @@ -150,6 +150,8 @@ struct fastopen_queue {
> spinlock_t lock;
> int qlen; /* # of pending (TCP_SYN_RECV) reqs */
> int max_qlen; /* != 0 iff TFO is currently enabled */
> +
> + struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
> };
>
> /** struct request_sock_queue - queue of request_socks
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 3b3b9b968e2d..1efe8365cb28 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -1555,9 +1555,10 @@ struct tcp_fastopen_request {
> int copied; /* queued in tcp_connect() */
> };
> void tcp_free_fastopen_req(struct tcp_sock *tp);
> -
> +void tcp_fastopen_destroy_cipher(struct sock *sk);
> void tcp_fastopen_ctx_destroy(struct net *net);
> -int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len);
> +int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
> + void *key, unsigned int len);
> void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
> struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
> struct request_sock *req,
> diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> index 15c25eccab2b..69c7493e42f8 100644
> --- a/include/uapi/linux/tcp.h
> +++ b/include/uapi/linux/tcp.h
> @@ -119,6 +119,7 @@ enum {
> #define TCP_FASTOPEN_CONNECT 30 /* Attempt FastOpen with connect */
> #define TCP_ULP 31 /* Attach a ULP to a TCP connection */
> #define TCP_MD5SIG_EXT 32 /* TCP MD5 Signature with extensions */
> +#define TCP_FASTOPEN_KEY 33 /* Set the key for Fast Open (cookie) */
>
> struct tcp_repair_opt {
> __u32 opt_code;
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index cac8dd309f39..81d218346cf7 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -284,7 +284,8 @@ static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
> ret = -EINVAL;
> goto bad_key;
> }
> - tcp_fastopen_reset_cipher(net, user_key, TCP_FASTOPEN_KEY_LENGTH);
> + tcp_fastopen_reset_cipher(net, NULL, user_key,
> + TCP_FASTOPEN_KEY_LENGTH);
> }
>
> bad_key:
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 3b34850d361f..8b1fa4dd4538 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -2571,6 +2571,17 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
> release_sock(sk);
> return err;
> }
> + case TCP_FASTOPEN_KEY: {
> + __u8 key[TCP_FASTOPEN_KEY_LENGTH];
> +
> + if (optlen != sizeof(key))
> + return -EINVAL;
> +
> + if (copy_from_user(key, optval, optlen))
> + return -EFAULT;
> +
> + return tcp_fastopen_reset_cipher(net, sk, key, sizeof(key));
> + }
> default:
> /* fallthru */
> break;
> @@ -3157,6 +3168,28 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
> return -EFAULT;
> return 0;
>
> + case TCP_FASTOPEN_KEY: {
> + __u8 key[TCP_FASTOPEN_KEY_LENGTH];
> + struct tcp_fastopen_context *ctx;
> +
> + if (get_user(len, optlen))
> + return -EFAULT;
> +
> + rcu_read_lock();
> + ctx = rcu_dereference(icsk->icsk_accept_queue.fastopenq.ctx);
> + if (ctx)
> + memcpy(key, ctx->key, sizeof(key));
> + else
> + len = 0;
> + rcu_read_unlock();
> +
> + len = min_t(unsigned int, len, sizeof(key));
> + if (put_user(len, optlen))
> + return -EFAULT;
> + if (copy_to_user(optval, key, len))
> + return -EFAULT;
> + return 0;
> + }
> case TCP_THIN_LINEAR_TIMEOUTS:
> val = tp->thin_lto;
> break;
> diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
> index 7ee4aadcdd71..21075ce19cb6 100644
> --- a/net/ipv4/tcp_fastopen.c
> +++ b/net/ipv4/tcp_fastopen.c
> @@ -29,7 +29,7 @@ void tcp_fastopen_init_key_once(struct net *net)
> * for a valid cookie, so this is an acceptable risk.
> */
> get_random_bytes(key, sizeof(key));
> - tcp_fastopen_reset_cipher(net, key, sizeof(key));
> + tcp_fastopen_reset_cipher(net, NULL, key, sizeof(key));
> }
>
> static void tcp_fastopen_ctx_free(struct rcu_head *head)
> @@ -40,6 +40,16 @@ static void tcp_fastopen_ctx_free(struct rcu_head *head)
> kfree(ctx);
> }
>
> +void tcp_fastopen_destroy_cipher(struct sock *sk)
> +{
> + struct tcp_fastopen_context *ctx;
> +
> + ctx = rcu_dereference_protected(
> + inet_csk(sk)->icsk_accept_queue.fastopenq.ctx, 1);
> + if (ctx)
> + call_rcu(&ctx->rcu, tcp_fastopen_ctx_free);
> +}
> +
> void tcp_fastopen_ctx_destroy(struct net *net)
> {
> struct tcp_fastopen_context *ctxt;
> @@ -55,10 +65,12 @@ void tcp_fastopen_ctx_destroy(struct net *net)
> call_rcu(&ctxt->rcu, tcp_fastopen_ctx_free);
> }
>
> -int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len)
> +int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
> + void *key, unsigned int len)
> {
> - int err;
> struct tcp_fastopen_context *ctx, *octx;
> + struct fastopen_queue *q;
> + int err;
>
> ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
> if (!ctx)
> @@ -79,27 +91,39 @@ error: kfree(ctx);
> }
> memcpy(ctx->key, key, len);
>
> - spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
>
> - octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
> - lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
> - rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
> - spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
> + if (sk) {
> + q = &inet_csk(sk)->icsk_accept_queue.fastopenq;
> + spin_lock_bh(&q->lock);
> + octx = rcu_dereference_protected(q->ctx,
> + lockdep_is_held(&q->lock));
> + rcu_assign_pointer(q->ctx, ctx);
> + spin_unlock_bh(&q->lock);
> + } else {
> + spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
> + octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
> + lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
> + rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
> + spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
> + }
>
> if (octx)
> call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
> return err;
> }
>
> -static bool __tcp_fastopen_cookie_gen(struct net *net,
> - const void *path,
> +static bool __tcp_fastopen_cookie_gen(struct sock *sk, const void *path,
> struct tcp_fastopen_cookie *foc)
> {
> struct tcp_fastopen_context *ctx;
> bool ok = false;
>
> rcu_read_lock();
> - ctx = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
> +
> + ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
> + if (!ctx)
> + ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
> +
> if (ctx) {
> crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
> foc->len = TCP_FASTOPEN_COOKIE_SIZE;
> @@ -115,7 +139,7 @@ static bool __tcp_fastopen_cookie_gen(struct net *net,
> *
> * XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
> */
> -static bool tcp_fastopen_cookie_gen(struct net *net,
> +static bool tcp_fastopen_cookie_gen(struct sock *sk,
> struct request_sock *req,
> struct sk_buff *syn,
> struct tcp_fastopen_cookie *foc)
> @@ -124,7 +148,7 @@ static bool tcp_fastopen_cookie_gen(struct net *net,
> const struct iphdr *iph = ip_hdr(syn);
>
> __be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
> - return __tcp_fastopen_cookie_gen(net, path, foc);
> + return __tcp_fastopen_cookie_gen(sk, path, foc);
> }
>
> #if IS_ENABLED(CONFIG_IPV6)
> @@ -132,13 +156,13 @@ static bool tcp_fastopen_cookie_gen(struct net *net,
> const struct ipv6hdr *ip6h = ipv6_hdr(syn);
> struct tcp_fastopen_cookie tmp;
>
> - if (__tcp_fastopen_cookie_gen(net, &ip6h->saddr, &tmp)) {
> + if (__tcp_fastopen_cookie_gen(sk, &ip6h->saddr, &tmp)) {
> struct in6_addr *buf = &tmp.addr;
> int i;
>
> for (i = 0; i < 4; i++)
> buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
> - return __tcp_fastopen_cookie_gen(net, buf, foc);
> + return __tcp_fastopen_cookie_gen(sk, buf, foc);
> }
> }
> #endif
> @@ -313,7 +337,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
> goto fastopen;
>
> if (foc->len >= 0 && /* Client presents or requests a cookie */
> - tcp_fastopen_cookie_gen(sock_net(sk), req, skb, &valid_foc) &&
> + tcp_fastopen_cookie_gen(sk, req, skb, &valid_foc) &&
> foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
> foc->len == valid_foc.len &&
> !memcmp(foc->val, valid_foc.val, foc->len)) {
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 5418ecf03b78..d80e1313200a 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1892,6 +1892,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
>
> /* If socket is aborted during connect operation */
> tcp_free_fastopen_req(tp);
> + tcp_fastopen_destroy_cipher(sk);
> tcp_saved_syn_free(tp);
>
> sk_sockets_allocated_dec(sk);
> --
> 2.15.0.rc1.287.g2b38de12cc-goog
>
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